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on Beams.

447

Example 23.  (i) A team 2' long- x i" square is broken by 250 Ibs.
at the centre. (2) Find the breaking load for a. beam 10 ft. long,
10" deep, and 6" wide, with the load 2 ft. from one end. (Eng.
Exam. 1886.)

For (i) (keeping- /in feet and bh in ins.)

^                _

"    4   ~"'    6   . ~
For (2) by Case IV., Fig. 397

4x1x1

_
~75

=?

5

/                10

--   and W-/*~ x 5 - 75Q x 6 x IQQ x 5
6            y   6x8              6x8

= 46875 Ibs. = 20-9 tons.

\

r^Q. 406

Example 24.  A shaft pulley is 8' from one bearing and 2' from
the other. Weight of sliaft = 20o Ibs. Weight of pulley = 50 Ibs.
Total belt tension (downwards) = 100 Ibs. Draw bending- moment
diagram and find loads on bearing's. (Eng. Exam, 1888.)

t>           ^   r       '    L       W/       200X10            _,      f

Bm of shaft weight = -g- =5 =250 Ib. ft.
' .............. - '-                            o    .         <>           ........ r   .............. -"

Reactions due to pulley and strap =  x 150= 30 Ibs.

and  x 1 50= 120 Ibs.
10      3

" Bm due to ptilley weight and strap pull =30x8 or 120 x 2 = 240 Ib. ft.
Jl^=ioo-f- 30= 1 50 lips.
Rt2 = 100+120= 220 Ibs.

And the diagrams are shewn .at Fig. 406, Bf being the combined
figure.            '     ,                                             i   -